1. Field of the Invention
The present invention relates to the field of switched telephony, and in particular, to wireless digital subscriber services, such as asymmetric digital subscriber line (ADSL) services, that provide fixed broadband data access to remote locations.
2. Background of the Invention
As electronic communication by businesses and private individuals has increased, the demand on network service providers for high speed, i.e., broadband, data transmission has steadily grown. Originally, service providers attempted to meet such demand with narrow band analog modems over traditional circuit-switched communication networks. However, these networks unnecessarily consumed resources because they set aside direct lines for data transmission even when no voice or data was being transmitted. Thus, to utilize network resources more efficiently than the circuit-switched communication networks, service providers are increasingly turning to packet-switched communication and broadband data services.
Packet-switched communication utilizes network capacity only when transferring voice or data. Data is sliced into small packets of information that are transmitted when a circuit is available. Circuits are not dedicated to certain user applications, as a phone service would be in a circuit-switched network. Instead, circuits remain open and available to all on-line users whenever they have data packets to transmit. This allocation strategy keeps lines open and saves network resources until they are actually needed for communication.
To accomplish this packet-switched broadband data communication, traditional network service providers typically use one of the following deployment options: (1) ADSL service using wired landlines (wireline ADSL); (2) integrated fiber in the loop (IFITL); or (3) ISDN, X.25, and other similar deployment services. In the prior art, the network service providers that own these wired telephone lines prefer wireline ADSL to deliver packet-switched data communication in service areas highly concentrated with customers because existing wire lines can be used, making ADSL inexpensive relative to the customer revenue produced in concentrated areas. However, broadband data rates over wire line facilities are distance dependent and require digital carrier systems for support once the length of wire line facilities exceed three miles from the central office. In contrast, in less concentrated and remote areas (e.g., rural areas), the smaller number of potential customers typically does not offer enough revenue to outweigh the costs to install and maintain the system. In addition, the longer deployment distances require more engineering efforts and capital investment in the improvement of line qualification to achieve expected transmission efficiency and quality. Therefore, potential customers in many locations typically do not have access to wireline ADSL service.
IFITL deployment improves the efficiency and quality of transmission over greater distances as compared to the wireline ADSL. However, the cost of installing optical fiber lines is very high, such that the limited numbers of distant potential customers would rarely, if ever, justify the initial investment.
Thus, there remains a need for a supplemental service that extends existing packet-switch data networks to less populated and remote areas that currently have no access. The deployment technique should be economical to install and should not suffer from reduced transmission quality over long distances. Further, the deployment method should enable network service providers to furnish remote customers with data access, while still realizing a profit.
The present invention is a fixed broadband wireless data access service that provides broadband packet-switched data transport for high speed data access. It will be described herein in terms of ADSL, but it could be applied in other contexts, such as wireless integrated service digital network over digital subscriber line (IDSL), wireless very high bit rate digital subscriber line (VDSL), or wireless symmetric or single-line digital subscriber line (SDSL). The following publications describe the broadband data communications to which this invention can be applied and are hereby incorporated by reference: (1) Goralski, Walter, SONET: A Guide to Synchronous Optical Networks, McGraw-Hill Companies, May 1997; (2) Stallings, William, ISDN and Broadband ISDN with Frame Relay and ATM, 4th Edition, Prentice Hall, Inc., October 1998; and (3) Sexton, Mike, and Reid, Andy, Broadband Networking: ATM, SDH, and SONET, Artech House, January 1997. Additionally, the present invention will be described herein in terms of an asynchronous transfer mode (ATM) network protocol, but should be understood to apply to other packet-switched data protocols, such as Internet Protocol (IP) over the air.
Based on asynchronous transfer mode technology, wireless ADSL supplements an existing packet-switched data network to extend high speed data services to remote locations. The wireless ADSL network is a point-to-multipoint cellular-type network that connects to a data service provider (e.g., an internet service provider or corporate local access network) through an existing ATM regional broadband network (also referred to as a backbone network). The following publications describe the ADSL and ATM technology and are hereby incorporated by reference: (1) Goralski, Walter, ADSL and DSL Technologies, McGraw-Hill Series on Computer Communications, 1998, ISBN 0-07-024679-3; and (2) ADSL Documents of ITU Standard, T1E1.413. Also incorporated by reference, similar publications describing IDSL, VDSL, and SDSL are: (1) Starr, Cioffi, and Silverman, Understanding Digital Subscriber Line Technology, Prentice Hall 1999, ISBN 0137805454; (2) Roberts, R., VDSL Out-of-Band Spectral Roll-off: FCC Part 15 Compliance Based Upon Flat-Pair Distribution-Cable Radiation, ANSI T1E1.4/97-244, Minneapolis, Minn., September 1997; and (3) Cioffi, John, VDSL System Requirements Document, ANSI Contribution T1E1.4/98-043R3, June 1998. In addition, U.S. Pat. No. 5,479,447, issued Dec. 26, 1995 to Chow et al., discloses a method and apparatus for adaptive, variable-bandwidth, high speed data transmission of a multicarrier signal over digital subscriber lines, and is hereby incorporated by reference.
To support multiuser service sessions by wireless transmission, the present invention employs a data protocol of shared access bandwidth with adaptive asymmetric data rates. The strategy of sharing bandwidth by time allows several customers to simultaneously interface with a wireless transmitter/receiver connected to the ATM backbone. Additionally, adaptive asymmetric data rate protocols optimize the communication between the multiple customers and the wireless transmitter/receiver. The asymmetric data rate protocol tailors the data streams between the customer and wireless transmitter/receiver to accommodate changes in the amount of data that must be transmitted. Communication travels back and forth between the customer equipment and the wireless transmitter/receiver such that one side transmits data and then listens for transmissions by the other side. As a result, the wireless data protocol of the present invention fully integrates the wireless multiuser high speed data access service with the wireline regional broadband network and the connected data service providers.
As shown in FIG. 1, the present invention builds upon the ATM switch of an existing regional broadband network. Base stations located nearest to the ATM switch are connected through wireline or wireless backhaul links to the ATM switch (FIG. 1 shows wireline backhaul links, but wireless backhaul links could also be used). A base station includes xe2x80x9ctrans/ceiver radioxe2x80x9d, xe2x80x9cRF channel combinerxe2x80x9d, and/or any kind of filters. Backhaul links are the transmission facilities, like transport trunks carrying concentrated user data and network signaling, that support the duplex communications between customer ends and a central location such as a switch or service provider""s network. Each base station, consisting of wireless transmission equipment, is centrally located in a network cell to provide shared high speed wireless access to each customer covered by the same transmitter/receiver antenna at the cell hub. The customers within the cells each have wireless customer equipment for communicating with the base station equipment. The base stations are connected to the nearest ATM switch through backhaul links that can be radio-frequency (RF) backhaul links, land line backhaul links, or a combination of the two. Cells are linked together on backhaul facilities to the ATM switch. The layers of linked cells produce a network of integrated broadband data service that uses wireless technology to deliver high speed data access to previously unreachable areas.
Also connected to the ATM switch is a network management system (NMS) that provides a network view of all its managed elements. The NMS controls and monitors the end-to-end operations of the wireless ADSL network, such operations including network creation, flow-through provisioning, fault and performance management, capacity and traffic management, accounting management, and security management.
The present invention uses a data management strategy that provides customers with seamless data transfer. Although customers within a cell share packet-switched data connections over the air, the wireless ADSL network provides each customer with an individual permanent virtual connection that provides continuous high speed data access. In the preferred embodiment, the present invention supports a wide range of packet-switched data services, e.g., internet access, on-line web browsing, wireless VoIP (voice over internet protocol), wireless voice service, interactive video services, nomadic wireless data access, and broadband mobile data access.
To provide uninterrupted service, the downstream bandwidth from the network to the customer or the upstream bandwidth from the customer to the network can be engineered in various symmetric and asymmetric configurations. In the preferred embodiment, the particular data traffic management configuration is tailored to meet the needs of individual customers. The base stations communicate with customer radio equipment that links to an Ethernet or ATM interface on the customer""s network, depending on the interface required by the customer""s network model. The customer radios in each cell share the same down-link wireless data channel, and send user traffic data back to the base station. The mode of transmission from a base station to customer radios is point-to-multipoint, while the mode of transmission from an individual customer radio to a base station is point-to-point.
Accordingly, it is an object of the present invention to provide economic high speed data access to customers in locations where wireline ADSL and IFITL service is not available.
It is another object of the present invention to provide a wide range of packet-switched data services to multiple consumers using shared wireless packet-switched data connections.
These and other objects of the present invention are described in greater detail in the detailed description of the invention, the appended drawings, and the attached claims.